Germanium Hydrides Research Articles

Small Molecule Activation by 4‐N,N‐Dimethylaminopyridine‐Stabilized Bis(silyl)germylenes

AbstractThe synthesis, characterization, and reactivity of DMAP⋅Ge(SitBu3)Si(TMS)3 1 a and DMAP⋅Ge[Si(TMS)3]2 1 b are reported (DMAP = 4‐N,N‐Dimethylaminopyridine). These germylenes were isolated in moderate yields by the reaction of DMAP⋅GeCl2 with NaSitBu3⋅(THF)2 and KSi(TMS)3⋅(THF)1.2 or 2 equivalents of KSi(TMS)3⋅(THF)1.2, respectively, at low temperature (TMS = Trimethylsilyl). Exposure of 1 a to dihydrogen forms the tetravalent germanium hydride species GeH2(SitBu3)Si(TMS)3 2 a. Additionally, the reactivity of 1 a,b towards the substitution of 2,6‐dimethylphenyl isocyanide (CNXyl) 3 a,b, the alkyne cycloaddition of diphenylacetylene (PhCCPh) 4 a,b, and the substitution of DMAP for NHC using 1,3,4,5‐tetramethylimidazol‐2‐ylidene (IMe4) 5 a,b was investigated (NHC = N‐heterocyclic carbene). Reaction products were characterized by multinuclear magnetic resonance (NMR), infrared (IR) spectroscopy, mass spectrometric analysis, and single‐crystal X‐ray diffraction (SC‐XRD) study.

Group superatoms: A new concept in cluster science

A promising research area in nanomaterials is the use of superatomic clusters as building blocks for creating novel molecules or materials with tailored properties. However, assembling these superatoms into functional materials is challenging, and a thorough understanding of this process is still lacking. In this study, we introduce a new concept called the “superatomic family,” which refers to superatoms that share similar valence electron structures but differ in size. We demonstrate this concept with the synthesized [Au6{Ni3(CO)6}4]2− cluster and the designed [Au16{Ni6(CO)10}4]2− and [Au31{Ni10(CO)15}4]5− clusters. These serve as analogs to simple hydrocarbons, such as methane (CH4), silicon hydride (SiH4), and germanium hydride (GeH4). In these supermolecular structures, the central cores of Au6, Au16, and Au31 exhibit the formation of superatomic SP3 hybridized orbitals, which influence the molecular shape and bonding. Moreover, we explored superatomic bonding involving SP3–SP3 hybridized cores, representing a single superatomic bond between members of the superatomic family, analogous to CH3–SiH3 bonds. By integrating the concept of group superatoms into the Lewis structure framework, we present a powerful approach for predicting and engineering cluster properties, thus opening a vast landscape of nanomaterial design possibilities.

Pt(II) complexes bearing P,N-donor ligands as catalysts in chemoselective hydrosilylation, hydrogermylation, and hydroboration of terminal alkenes

In this report, we present the synthesis of six novel neutral platinum complexes employing readily available P,N-donor ligands through a straightforward two-step procedure. Subsequently, we investigated their catalytic activity in the hydroelementation of terminal olefins, highlighting their versatile utility in material and natural product chemistry. The efficient addition of silicon, germanium, and boron hydrides to the CC bond at low catalyst loading occurred exclusively in an anti-Markovnikov manner. Furthermore, our substrate scope encompasses a wide range of aliphatic and aromatic alkenes, featuring substituents with varying electronic properties. In contrast to many previous Pt-complexes, our catalytic system displayed exceptional chemoselectivity towards other unsaturated functional groups, such as carbonyl and internal CC bonds. Notably, it also exhibited remarkable tolerance to hydroxyl, alkoxyl, silyl, and thioether moieties. Additionally, we accentuated the prowess of our catalyst, showcasing its capability to sustain consistent activity and selectivity throughout numerous catalytic cycles.

Low-valent germanium and tin hydrides as catalysts for hydroboration, hydrodeoxygenation (HDO), and hydrodesulfurization (HDS) of heterocumulenes.

The low-valent germanium and tin hydrides, [LMH; L = {(ArHN)(ArN)-CN-C(NAr)(NHAr); Ar = 2,6-Et2-C6H3}; M = Ge; (Ge-1), Sn (Sn-2)] bearing bis-guanidinato anions are employed as catalysts for chemoselective reduction of heterocumulenes via hydroboration reactions. This protocol demonstrates that a wide range of carbodiimides (CDI), isocyanates, isothiocyanates, and isoselenocyanates undergo partial reduction, yielding the corresponding N-boryl formamidine, N-boryl formamide, N-boryl thioformamide, and N-boryl selenoformamide products, respectively. Isocyanates and isothiocyanates are further converted into N-boryl methyl amines through hydrodeoxygenation (HDO) and hydrodesulfurization (HDS) reactions in the presence of catalyst Ge-1. Additionally, catalyst Sn-2 exhibits excellent inter and intra-molecular chemoselectivity over other functional groups. Based on stoichiometric experiments, a plausible catalytic cycle for chemoselective hydroboration of heterocumulenes is proposed.

Revealing Capacity Degradation of Ge Anodes in Lithium‐Ion Batteries Triggered by Interfacial LiH

AbstractThe Germanium (Ge), as a fast‐charging and high specific capacity (1568 mAh g−1) alloy anode, is greatly hampered in practical application by poor cyclability. To date, the understanding of cycling performance degradation remains elusive. This study illustrates that, contrary to conventional beliefs, most of the Ge material in failed anodes still retains good integrity and does not undergo severe pulverization. It is revealed that capacity degradation is clearly correlated to the interfacial evolution of lithium hydride (LiH). Tetralithium germanium hydride (Li4Ge2H), as a new species derived from LiH, is identified as the culprit of Ge anode degradation, which is the dominant crystalized component in an ever‐growing and ever‐insulating interphase. The significantly increased thickness of the solid electrolyte interface (SEI) is accompanied by the accumulation of insulating Li4Ge2H upon cycling, which severely retards the charge transport process and ultimately triggers the anode failure. We believe that the comprehensive understanding of the failure mechanism presented in this study is of great significance to promoting the design and development of alloy anode for the next generation of lithium‐ion batteries.

Revealing Capacity Degradation of Ge Anodes in Lithium-Ion Batteries Triggered by Interfacial LiH.

The Germanium (Ge), as a fast-charging and high specific capacity (1568 mAh g-1 ) alloy anode, is greatly hampered in practical application by poor cyclability. To date, the understanding of cycling performance degradation remains elusive. This study illustrates that, contrary to conventional beliefs, most of the Ge material in failed anodes still retains good integrity and does not undergo severe pulverization. It is revealed that capacity degradation is clearly correlated to the interfacial evolution of lithium hydride (LiH). Tetralithium germanium hydride (Li4 Ge2 H), as a new species derived from LiH, is identified as the culprit of Ge anode degradation, which is the dominant crystalized component in an ever-growing and ever-insulating interphase. The significantly increased thickness of the solid electrolyte interface (SEI) is accompanied by the accumulation of insulating Li4 Ge2 H upon cycling, which severely retards the charge transport process and ultimately triggers the anode failure. We believe that the comprehensive understanding of the failure mechanism presented in this study is of great significance to promoting the design and development of alloy anode for the next generation of lithium-ion batteries.

Light‐Promoted Germylation of Aryl Propiolamides/Alkynoates: Synthesis of Ge‐Containing Spiro[4.5]trienones and Vinylgermanes

AbstractThe light‐promoted regioselective germylation of aryl propiolamides/alkynoates with germanium hydrides is reported. The germyl‐containing spiro[4.5]trienones were obtained when N‐arylpropiolamides were used via sequential C−Ge and C−C bond formation, while aryl alkynoates delivered the vinylgermanes with radical Smiles rearrangement and CO2 release.

Germanium hydrides as an efficient hydrogen-storage material operated by an iron catalyst.

The use of metal hydrides such as NaBH4 as hydrogen-storage materials has recently received substantial research attention on account of the worldwide demand for the development of efficient hydrogen-production, -storage, and -transportation systems. Here, we report the quantitative production of H2 gas from a germanium hydride, Ph2GeH2, mediated by an iron catalyst at room temperature via dehydrogenative coupling, concomitant with the formation of (GePh2)5. Of particular importance is that Ph2GeH2 can be facilely recovered from (GePh2)5 by contact with 1 atm of H2 or PhICl2/LiAlH4 at 0 °C or 40 °C, respectively. A detailed reaction mechanism for the iron-catalyzed dehydrogenative coupling of Ph2GeH2 is proposed based on the isolation of four intermediate iron species.

Redox flexibility in a germanium hydride manifold: hydrogen shuttling via oxidative addition and reductive elimination.

We report the synthesis of a trimetallic mixed-valence Ge(I)/Ge(II)/Ge(III) trihydride, which presents a structural novel motif among systems of the type (XMH)n (M = group 14 metal). In terms of reactivity (ArNiPr2)GeGe(ArNiPr2)(H)Ge(ArNiPr2)(H)2 can act as a source of both the Ge(II) and Ge(IV) hydrides via Ge-H reductive elimination from the central metal centre involving two different regiochemistries.

Copper-Catalyzed Germyl-Azidation of Alkenes with Germanium Hydrides and Trimethylsilyl Azide.

The incorporation of a germyl group and another functional fragment across the C═C bond is a challenging task due to the prevailing hydrogermylation reaction. Herein, an efficient copper-catalyzed three-component reaction of alkenes, germanium hydrides, and trimethylsilyl azide has been disclosed. This transformation allows the concomitant introduction of germyl and azide groups across the double bonds in a highly regioselective manner with tert-butyl hydroperoxides as the bystanding oxidant. The resulting β-germyl azides could be easily converted into β-germyl amine and 1,2,3-triazoles of significant value.

Germanium Hydride Catalyzed Selective Hydroboration and Cyanosilylation of Ketones

AbstractTwo new examples of β‐diketiminate or NacNac analogues, i. e., conjugated bis‐guanidinate (CBG) stabilized low valent germanium chloride (1) and germanium hydride (2) complexes, are reported. Deprotonation of LH upon treatment with n‐BuLi and an in situ generated LLi further treated with GeCl2⋅dioxane afforded LGeCl in 79 % yield. Compound 1 reacted with hydride source NaHBEt3 in toluene, afforded Ge (II) hydride (2) in 76 % yield. Both compounds 1 and 2 were characterized by NMR and mass spectroscopic methods. Further, germanium hydride catalyzed hydroboration and cyanosilylation of a wide range of ketones have been investigated. Control reactions suggest hydroboration reactions occurred via insertion and Ge−O/B−H bond metathesis pathways. It is worthy of mentioning that, in the case of hydroboration of ketones, reducible groups such as alkene, alkyne, halide, ester, nitro, and heterocycles were untouched. Furthermore, compound 2 was employed for the reduction of carbonate, formate, and anhydride substrates via the hydroboration technique.

Direct C-H Dehydrogenative Germylation of Terminal Alkynes with Hydrogermanes.

A direct C(sp)-H germylation of terminal alkynes with triethyl germanium hydride is reported. The method is operationally simple and makes use of B(C6F5)3 catalysis in combination with 2,6-lutidine as an organic base. Exclusive selectivity for dehydrogenative germylation of the alkyne over the competing hydrogermylation is observed.

Copper-Catalyzed Three-Component Germyl Peroxidation of Alkenes.

The concurrent incorporation of a germyl fragment and another functional group (beyond the hydrogen atom) across the C═C double bond is a highly appealing yet challenging task. Herein we demonstrate the efficient germyl peroxidation of alkenes with germanium hydrides and tert-butyl hydroperoxide via a copper-catalyzed three-component radical relay strategy. This protocol exhibits excellent functional group tolerance and exquisite chemo- and regioselectivity under mild conditions and represents a rare example of constructing synthetically challenging metal-embedded organic peroxides.

New insights into the selective and systematic preparation of arylgermanium hydrides

A series of novel arylgermanium hydrides ArnGeH4–n (n = 1–3) and diaryl(chloro)germanium hydrides Ar2Ge(Cl)H were synthesized and characterized. Systematic preparation and purification were achieved via the lithium chloride–triflic acid and the optimized Grignard route. Arylgermanium hydrides ArnGeH4–n (Ar = 2,5-Me2C6H3, n = 1–3) were characterized by 1H and 73Ge NMR spectroscopy and single crystal X-ray diffractometry.

A Novel Approach for the Determination of the Ge Isotope Ratio Using Liquid-Liquid Extraction and Hydride Generation by Multicollector Inductively Coupled Plasma Mass Spectrometry.

In this work, a method for the accurate and precise determination of the Ge isotope ratio in synthetic water and natural samples of geological origin using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) with hydride generation was developed. The method was based on the liquid–liquid extraction of Ge to eliminate all elements affecting the generation of germanium hydrides. The standard-sample bracketing method was used to correct instrumental bias. Registration of analytical signal in time-resolved mode gave way to choose signals with best parameters and improved the precision of the results. Controlling the pH by using acetic buffer boosted the sensitivity by nearly five times in comparison to hydride generation methods suggested by other authors. The newly developed method is much simpler and quicker, does not need laborious Ge separation with ion-exchange resins, and thanks to its superior sensitivity, allows measurements of the Ge isotopic ratio in materials with relatively low Ge content. Delta values of the 74Ge/70Ge isotope ratio were measured in standard reference materials for which reference values were available in the GeoREM database. We demonstrated that the accuracy and precession of this method are equally good or better than methods proposed by other authors.

Superconducting germanium hydride with A15 structure

The possibility of the formation of A15 germanium hydride is investigated theoretically by the density functional method. It is shown that A15 germanium hydride Ge2H6 is stable in a certain pressure range of about 125 GPa. The results of calculations of the structural, phonon and electronic properties, energy characteristics of the normal phase are presented. The critical temperature of the superconducting transition is estimated.

Germanium Hydride Radical Trapped during the Photolysis/Thermolysis of Diarylgermylene.

Herein, we report the characterization of a novel germanium hydride radical arising from the photolysis/thermolysis of the diarylgermylene GeR2 [R = terphenyl: AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2 or AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2] by using electron paramagnetic resonance spectroscopy complemented with theoretical calculations. The trapped germanium radical is a pseudoplanar S = 1/2 germanium(III) hydride, i.e., •GeHRR' (R = AriPr4 or AriPr6; R' is a quaternary carbon), with a g tensor of [2.029, 2.003, 1.990], a 73Ge hyperfine tensor of [-10, -90, -10] MHz, and a strong 1H hyperfine tensor of [-23.0, -20.5, -31.5] MHz for the hydride. The germanium(III) hydride radical is a result of the insertion of a germanium(I) radical intermediate (:ĠeR) in a C-H bond, due to the greater reactivity of the germanium(I) radical intermediate in comparison with the tin(I) counterpart that we trapped earlier.

Thermodynamic properties of superconducting GeH3 under high pressure

Chemical precompression can reduce the pressure required for structure metallization and for the subsequent existence of a superconducting state in hydrogen-rich compounds. In this study, we determined the thermodynamic properties of the superconducting state in germanium hydride GeH3. Stable structures of this compound crystallize at 175 GPa during the chemical decomposition of GeH4. Computations were conducted within the formalism of the Eliashberg theory of superconductivity. This approach allowed us to analyze thermodynamic quantities such as the transition temperature (Tc), free energy, entropy, and specific heat difference (ΔF, ΔS, ΔC) between the superconducting and normal states. Results were obtained for three stable structures comprising A15 (Pm3¯n, fcc), Cccm (orthorhombic), and P42/mmc (tetragonal) for GeH3 at 180 GPa. The transition temperature for μ⋆ = 0.1 indicated substantial changes between the crystal structures, where A15 had the highest Tc (194 K). The Cccm and P42/mmc systems had similar critical temperatures of 147.2 K and 132.9 K, respectively. The advantageous superconducting state properties of the A15 system in terms of the thermodynamic quantities make this structure more desirable for industrial use. In particular, the free energy difference representing the thermodynamic stability of the superconducting state was two times larger in A15 compared with the other systems. The results obtained for the critical temperatures were compared with the values obtained using the McMillan (MM) and Allen–Dynes (AD) analytic formulae. The difference between the results obtained using the Eliashberg formalism and MM approach was well above 60 K for the A15 structure (TcMM = 133 K, TcAD = 159 K). Further analysis with the Bardeen–Cooper–Schrieffer (BCS) constants (RΔ, RC, RH) showed that GeH3 cannot be considered as a BCS superconductor.

Reactivity of Monomeric N→Ge Coordinated Germanium(II) Hydrides

Monomeric organogermanium(II) hydrides {(LGeH)M(CO)5} (M = Cr (1), W (2), L = [2‐(CH2NEt2)‐4,6‐tBu2‐C6H2]–) were treated with ortho‐quinones and terminal alkyne HC≡CCO2Me to give {[(LH)Ge(κ2‐O2‐3,5‐tBu2C6H2)]M(CO)5} (M = Cr (3), W (4)), {[(LH)Ge(κ2‐O2‐3,4,5,6‐Cl4C6)]M(CO)5} (M = Cr (5), W (6)) and {[LGeCH=CH(COOMe)]Cr(CO)5} (11). These reactions proceeded as catalyst‐free reductions of C=O and C≡C bonds. Experimental data demonstrated zwitterionic character of Ge(II) complexes 3–6, where the 1,3,2‐benzodioxagermylenolato anion involving the GeO2C2 five membered ring coordinates the M(CO)5 fragment. This anionic part is compensated by the NHEt2 counter cation that is part of ligand L. Reactions of 1 and 2 differ mutually in the case of reduction of HC≡CCO2Me. The experimental and theoretical data suggest that compound 1 reacts with HC≡CCO2Me to give vinyl germylene 11 as the product of the anti‐Markovnikov cis‐1,2‐addition, while complex 2 is inactive. These results thus suggest that the reactivity of the terminal GeH bond may be tuned by its coordination to various transition metals.

Spin-Coupled Generalized Valence Bond Description of Group 14 Species: The Carbon, Silicon and Germanium Hydrides, XH n ( n = 1-4).

Although elements in the same group in the Periodic Table tend to behave similarly, the differences in the simplest Group 14 hydrides-XH n (X = C, Si, Ge; n = 1-4)-are as pronounced as their similarities. Spin-coupled generalized valence bond (SCGVB) as well as coupled cluster [CCSD(T)] calculations are reported for all of the molecules in the CH n/SiH n/GeH n series to gain insights into the factors underlying these differences. It is found that the relative weakness of the recoupled pair bonds of SiH and GeH gives rise to the observed differences in the ground state multiplicities, molecular structures, and bond energies of SiH n and GeH n. A number of factors that influence the strength of the recoupled pair bonds in CH, SiH, and GeH were examined. Two factors were identified as potential contributors to the decrease in the strengths of these bonds from CH to SiH and GeH: (i) a decrease in the overlap between the orbitals involved in the bond and (ii) an increase in Pauli repulsion between the electrons in the two lobe orbitals centered on the X atoms. Finally, an analysis of the hybridization of the SCGVB orbitals in XH4 indicates that they are closer to sp hybrids than sp3 hybrids, which implies that the underlying cause of the tetrahedral structure of the XH4 molecules is not a direct result of the hybridization of the X atom orbitals.